There are two ways to resist earthquakes: One is resisting, that is increasing the strength of a structure so as to ensure the safety of the structure when the structure is under the action of an earthquake with the expected intensity (FIGS. 1 and 3); the other is relieving, that is providing an earthquake-isolation layer with very small horizontal stiffness between the main structure and the basic structure, so that the main structure is basically isolated from the earth in the horizontal direction and the earthquake energy is not easy to spread to the main structure, thus avoiding damage of the main structure (as shown in FIGS. 2 and 4, in which the earthquake-isolation layer 26 is disposed between the main structure 27 and the base structure 28). For the main structure, the smaller the horizontal stiffness of the earthquake-isolation layer, the weaker the response of the upper structure to an earthquake will be. That is, for the action on an earthquake, the smaller the horizontal stiffness of the earthquake-isolation layer, the more advantageous it will be to the upper structure (FIG. 4). In FIGS. 3 and 4, the ground moves back and forth horizontally when an earthquake occurs.
On the other hand, the structure is resistant to a wind load. And the probability of the structure encountering strong winds is much higher than encountering strong earthquakes. For structural wind resistance, providing an earthquake-isolation layer is disadvantageous, and the smaller the horizontal stiffness of the earthquake-isolation layer, the more disadvantageous it will be to the upper structure (FIGS. 5 and 6). Therefore, an earthquake-isolation structure of a common earthquake-isolation layer is adopted, with the horizontal stiffness of the earthquake-isolation layer being a trade-off between the structural earthquake isolation and wind resistance.